guard against;beware of;be alert to;be cautious of;beware ;
例句:
We should lock doors and windows in order to prevent house-breaking.
我们要锁好门窗,谨防坏人溜门撬锁.
Guard against a hidden arrow.
谨防暗箭.
He is cautious of giving offence to others.
他谨防得罪人.